In certain applications of incandescent lamps, e.g., in automobile lighting, the lamp may be subjected to appreciable vibration and mechanical shock. Such vibration and shock can result from engine operation, travel over rough roads, impact to the car, and similar conditions. If the filament of such a lamp is of relatively heavy wire, e.g., the type typically used for brake lights, it can readily withstand such vibration and shock without damage
But if the filament is of the relatively fine-wire type, e.g., the type typically used for parking lights, it is usually much less rugged and much more suspectible to damage by such vibration aqd shock.
Efforts have previously been made to reduce the chance for damage to such fine-wire filaments by supporting the lamp on cushioning means that is capable of limiting the amount of vibration energy transmitted to the lamp. But the addition of such cushioning means for mounting the lamp involves extra expense t hat automobile manufacturers,understandably, prefer to avoid